Brake system for a motorcycle and a method of filling the brake system

ABSTRACT

A method of filling a brake system for a motorcycle including a brake system having a master cylinder assembly and a caliper assembly. The master cylinder assembly includes a housing and a cover coupled to the housing to define an enclosed reservoir. The caliper assembly includes a fluid passageway and a fitting adjustable to selectively provide fluid communication with the fluid passageway. The motorcycle also includes a brake line coupled between the master cylinder assembly and the caliper assembly to fluidly connect the reservoir and the fluid passageway. The method also includes substantially evacuating the reservoir, brake line and fluid passageway, coupling a fluid source to the fitting, passing fluid from the fluid source through the fitting, and filling the reservoir, brake line, and fluid passageway with the fluid passed through the fitting from the fluid reservoir.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of co-pending U.S. patentapplication Ser. No. 11/169,324, filed Jun. 28, 2005, the entirecontents of which are hereby incorporated by reference herein.

BACKGROUND

The present invention relates to brake systems for motorcycles, and moreparticularly to methods of filling brake systems for motorcycles.

Typical motorcycle brake systems include a master cylinder assembly, acaliper assembly, and a brake line coupling the master cylinder assemblyto the caliper assembly. Actuation of a hand lever of the mastercylinder assembly pressurizes brake fluid through the brake lines andinto the caliper assembly to press brake pads of the caliper assemblyagainst a wheel rotor to slow or stop the rotation of the wheel. Themaster cylinder assembly includes a reservoir that contains the brakefluid supplied to the brake system.

For the brake system to work properly, the entire brake system must befilled with the brake fluid, except for some allowable air at the top ofthe reservoir. It is known to fill the brake system with fluid byremoving a cover of the master cylinder assembly, filling the reservoirwith brake fluid, opening a bleeder fitting located on the caliperassembly, pumping the brake lever until the fluid exits the bleederfitting, and adding fluid to the reservoir as needed. When full, thecover is replaced and the bleeder fitting is closed. This process istime consuming and is not desirable for mass production.

In production, the fill process is performed after the brake system isattached to the motorcycle. Another known fill process used in thisenvironment is to remove the cover, attached an adapter to thereservoir, use the adapter to evacuate the air from the brake systemthrough the reservoir, use the adapter to fill the brake system withbrake fluid through the reservoir, remove the adapter exposing the fluidwithin the reservoir, and replacing the cover onto the housing to sealthe reservoir. The bleeder fitting remains closed throughout the entireprocess.

Other processes fill brake fluid from the bleeder fitting. In thisprocess, the cover is removed, the bleeder fitting is opened, an adapteris attached to the bleeder fitting, the adapter passes brake fluidthrough the bleeder fitting to fill the brake system, the cover isreplaced, the adapter is removed, and the bleeder fitting is closed.

These known fill processes generally have used either Dot 3, Dot 4, orDot 5 brake fluid. Due to fluid characteristics required by modernantilock braking systems, Dot 4 brake fluid is becoming more common. Dot4 brake fluid is more corrosive than Dot 5 brake fluid and has thepotential to damage the cosmetic appearance of certain components of themotorcycle, such as the painted tank, if spilled or splashed. Because ofthis potential for cosmetic damage, the known fill processes that fillthe brake system with the cover removed from the housing aredisadvantageous. In addition, it is time consuming to remove and replacethe cover during the fill process increasing process cycle times and themanufacturing expense of the motorcycle.

SUMMARY

The present invention provides a method of filling a motorcycle brakesystem having a master cylinder assembly and a caliper assembly. Themaster cylinder assembly includes a housing and a cover coupled to thehousing to define an enclosed reservoir. The caliper assembly includes afluid passageway and a bleeder fitting adjustable to selectively providefluid communication with the fluid passageway. The motorcycle alsoincludes a brake line coupled between the master cylinder assembly andthe caliper assembly to fluidly connect the reservoir and the fluidpassageway. The method includes substantially evacuating the reservoir,brake line and fluid passageway, coupling a fluid source to the fitting,passing fluid from the fluid source through the fitting, and filling thereservoir, brake line, and fluid passageway with the fluid passedthrough the fitting from the fluid reservoir.

The present invention also provides a master cylinder assembly for abrake system of a motorcycle. The master cylinder assembly includes ahousing, a cover, and a sight glass. The cover is coupled to the housingto define a reservoir adapted to contain a fluid. The sight glass isreceived within an aperture of the cover and is adapted to indicate thelevel of the fluid within the reservoir. The sight glass includes a topportion, a bottom portion, and a middle portion between the top andbottom portions. The top and bottom portions each include a perimetersized to be received within the aperture and to seal the reservoir, andthe middle portion includes a reduced perimeter relative to the top andbottom portions. The sight glass is movable between raised and loweredpositions. The bottom portion is received within the aperture and sealsthe reservoir in the raised position. The top portion is received withinthe aperture and seals the reservoir in the lowered position. The middleportion allows fluid flow through the aperture when the sight glass ismoved from the raised position to the lowered position.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a motorcycle, illustrating a brakesystem of the motorcycle embodying the present invention.

FIG. 2 is a partially exploded view of a portion of a steering assemblyof the motorcycle shown in FIG. 1, illustrating a master cylinderassembly and brake line of the brake system.

FIG. 3 is a partially exploded view of another portion of the steeringassembly shown in FIG. 1, illustrating a caliper assembly of the brakesystem.

FIG. 4 is an exploded view of the master cylinder assembly shown in FIG.2.

FIG. 5 is a cross section view of the master cylinder assembly takenalong line 5-5 of FIG. 4, illustrating the master cylinder assembly inthe assembled condition with a sight glass of the master cylinderassembly in the raised position.

FIG. 6 is a view similar to FIG. 5, illustrating a reservoir of themaster cylinder assembly filled with a fluid.

FIG. 7 is a view similar to FIG. 6, illustrating the sight glass betweenthe raised and lowered positions.

FIG. 8 is a view similar to FIG. 7, illustrating the sight glass in thelowered position.

FIG. 9 is a cross section view of an adapter used to couple to a bleederfitting of the caliper assembly of FIG. 3, illustrating the adapter inan unclamped position.

FIG. 10 is a view similar to FIG. 9, illustrating the adapter in aclamped position.

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass both direct and indirectmountings, connections, supports, and couplings. Further, “connected”and “coupled” are not restricted to physical or mechanical connectionsor couplings.

DETAILED DESCRIPTION

FIG. 1 illustrates a motorcycle 10 including a frame 12, a steeringassembly 14 pivotably mounted to a forward portion of the frame 12, afront wheel 16 rotatably mounted to an end of the steering assembly 14,a rear wheel 18 rotatably mounted to a swing arm 20 that is pivotablyconnected to a rearward portion of the frame 12, and anengine/transmission assembly 22 mounted to the frame 12 and operablycoupled to the rear wheel 18. The front wheel 16 includes a front rotor24 and the rear wheel 18 includes a rear rotor 26. A seat 28 is coupledto the frame 12 above the rear wheel 18 to support an operator. Thesteering assembly 14 includes a fork 30, handlebars 32, and controls,such as a throttle grip 34, coupled to the handlebars 32. The operatormanipulates the controls to power the engine/transmission assembly 22,drive the rear wheel 18, and propel the motorcycle 10. The operatormaneuvers the handlebars 32 to pivot the steering assembly 14 and frontwheel 16 to steer the motorcycle 10 while the motorcycle 10 is moving.

The motorcycle 10 also includes a braking system 36 including a frontbraking assembly and a rear braking assembly. The front braking assemblyincludes a master cylinder assembly 42 coupled to the handlebars 32, acaliper assembly 44 coupled to the fork 30, and a brake line 46 coupledbetween the master cylinder assembly 42 and caliper assembly 44. Therear braking assembly includes a master cylinder assembly coupled to alower portion of the frame 12, a caliper assembly 50 coupled to theswing arm 20, and a brake line (not shown) coupled between the mastercylinder assembly and caliper assembly 50.

With respect to the applicability of this invention, the front and rearbraking assemblies are substantially similar to each other andtherefore, only the front braking assembly will be discussed below indetail. It should be noted that one of ordinary skill in the art wouldreadily understand how the invention, as described below with respect tothe front braking assembly, could also be applied to the rear brakingassembly.

With reference to FIGS. 2 and 4, the master cylinder assembly 42includes a housing 52 and a cover 54 coupled to the housing 52 thattogether define a reservoir 56 for brake fluid 58. Typically, Dot 4 orDot 5 brake fluid is used. The cover 54 includes a central aperture 60and a flat annular top surface 62 around the aperture 60. The annularsurface 62 provides a mounting location for an annular warning label 64indicating proper care instructions and the contents of the reservoir56.

The master cylinder assembly 42 also includes a hourglass-shaped sightglass 66 that provides an external indication of the level of brakefluid 58 within the reservoir 56. The sight glass 66 includes a topportion 68, a bottom portion 70, and a middle portion 72 between the topand bottom portions 68, 70. The top and bottom portions 68, 70 eachinclude a larger perimeter than the perimeter of the middle portion 72.The sight glass 66 is movable between a raised position (FIGS. 5 and 6)where the bottom portion 70 is received within the aperture 60 and sealsthe reservoir 56 and a lowered position (FIG. 8) where the top portion68 is received within the aperture 60 and seals the reservoir 56. Themiddle portion 72 allows fluid flow through the aperture 60 when thesight glass 66 is moved from the raised position to the loweredposition. The top portion 68 includes a top flange 74 that has anincreased perimeter from the top portion 68 and that has a tapered topedge 76. The bottom portion 70 includes a bottom flange 78 that has anincreased perimeter from the bottom portion 70.

The housing 52 includes a clamp portion 80 that surrounds a portion ofthe handlebar 32. A clamp 82 surrounds the opposite portion of thehandlebar 32 and is fastened to the clamp portion 80 to secure thehousing 52 to the handlebar 32. The housing 52 also includes a clevisportion 84 including apertures 86. A hand lever 88 is pivotallyconnected to the housing 52 by positioning an apertured portion (notshown) of the hand lever 88 within the clevis 84 and inserting a pivotpin 90 through the apertures 86.

The master cylinder assembly 42 includes a gasket 92 positioned betweenthe housing 52 and the cover 54. The gasket 42 includes a perimeter 94,a central aperture 96, and a raised boss portion 98 surrounding theaperture 96. The perimeter 94 is compressed between the cover 54 and thehousing 52, and the raised boss portion 98 extends through the aperture60 of the cover 54 when the cover 54 and housing 52 are fastenedtogether (See FIG. 5). The gasket 92 also defines a baffled or ribbedportion 100 between the perimeter 94 and the central aperture 96. Theribbed portion 100 allows the gasket 92 to flex when acted upon byvarying pressure differences between the opposite sides of the gasket92.

The housing 52 includes a cavity (not shown) that is in fluidcommunication with the reservoir 56, which supplies fluid 58 to thecavity. The housing 52 also includes a brake line port 102 that is influid communication with the cavity. One end of the brake line 46 isfluidly coupled to the brake line port 102 to be in fluid communicationwith the cavity and the reservoir 56. The master cylinder assembly 42includes a piston (not shown) that is positioned within the cavity andthat is actuable upon pivoting of the hand lever 88. When the hand lever88 is pivoted, the piston moves within the cavity to pressurize thefluid 58 and move the fluid 58 through the port 102 and through thebrake line 46.

As shown in FIG. 3, the caliper assembly 44 includes a caliper housing104 that includes a brake line port 106, a fitting or bleeder fitting108, and an internal fluid passageway (not shown) that fluidly connectsthe brake line port 106 and the bleeder fitting 108. The bleeder fitting108 is selectively adjustable to provide access to the fluid passageway.The fluid passageway is also fluidly connected to multiple cavities (notshown) within the caliper housing 104. Each cavity houses a caliperpiston for movement within the cavity. The caliper assembly 44 alsoincludes two opposite facing brake pads (not shown) that are slidablymounted to the housing 104. The caliper assembly 44 is mounted to thefork 30 by bolts 110 such that a portion of the front rotor 24 isreceived within the housing 104 and between the brake pads. The oppositeend of the brake line 46 is fluidly coupled to the brake line port 106to be in fluid communication with the fluid passageways and thecavities. When the fluid 58 is pressurized by the piston in the mastercylinder assembly 42, the pressurized fluid 58 moves through the brakeline 46 and fluid passageway to fill the cavities and thereby move thepistons inwardly. This movement of the pistons causes the brake pads tobe pressed against the rotor 24 to thereby slow the rotation of therotor 24 and the front wheel 16 or resist rotation of the rotor 24 andthe front wheel 16.

The master cylinder assembly 42 is described with reference to FIGS. 4and 5. The warning label 64 is adhered to the annular surface 62 of thecover 54. Next, the raised boss portion 98 of the gasket 92 is insertedthrough the aperture 60 of the cover 54. The sight glass 66 is theninserted through the apertures 60, 96 in the cover 54 and the gasket 92from the bottom side of the cover 54 to a raised position. The taperededge 76 of the sight glass 66 provides a leading end to facilitate theentrance of the sight glass 66 through the apertures 60, 96. In theraised position, the middle and top portions 72, 68 of the sight glass66 are exposed above the surface of the cover 54. To protect the sightglass 66 from debris and damage while in the raised position, a cap 112is pressed over the sight glass 66 and held in place by the interferencebetween the top flange 74 and the inner wall of the cap 112. The cover54 and gasket 92 are then fastened to the empty housing 52 by insertingscrews (not shown) through the respective apertures in each component.The housing 52 is then attached to the handlebars 32 by fastening theclamp 82 to the clamp portion 80 around the handlebars 32.

The filling process of the brake system 36 is described with referenceto FIGS. 5-8. FIG. 5 illustrates the assembled master cylinder assembly42 without brake fluid. The sight glass 66 is in the raised position andthe bottom portion 70 creates a seal with the gasket 92 to seal thereservoir 56. To fill the brake system 36 with brake fluid 58, anadapter 40 is sealed to the bleeder fitting 108. The adapter 40, asshown in FIGS. 9 and 10, includes clamped and unclamped positions, andalso may be selectively coupled to a vacuum source and a source of brakefluid. The bleeder fitting 108 is then opened, and the adapter 40 isconnected to the vacuum source and evacuates fluid (air, moisture,liquid, etc.) from the reservoir 56, cavity of the housing 52, brakeline 46, passageway and cavities of the caliper assembly 44. The sightglass 66 includes a rib 114 between the middle portion 72 and the bottomportion 70. The rib 114 along with the interference fit between thebottom portion 70 and the gasket 92 resist movement of the sight glass66 into the reservoir 56 when the system is being evacuated. In otherembodiments, the sight glass 66 may not include rib 114, and theinterference fit between the bottom portion 70 and the gasket 92 issufficient to resist movement of the sight glass 66 into the reservoir.The vacuum can be held and monitored for a period of time to determineif there is any decay over the period of time, which could indicate aleak within the brake system 36. When the brake system 36 is evacuated,the ribbed portion 100 of the gasket 92 flexes downward caused by thepressure of the air remaining on the top side of the gasket 92.

If no decay is detected, the adapter 40 is connected to a source ofbrake fluid 58 and the fluid 58 is directed from the adapter 40 and intothe brake system 36 through the bleeder fitting 108. The fluid 58 can beintroduced for a specific period of time or until a specific pressure issurpassed. The bottom flange 78 and the interference fit between thebottom portion 70 and the gasket 92 resist movement of the sight glass66 out of the reservoir 56 when the system 36 is being filled. The fluid58 fills the entire reservoir 56 below the gasket 92, and the ribbedportion 100 of the gasket 92 returns to approximately its originalposition (FIG. 5). At this time, the adapter 40 goes into a scavengemode drawing back a portion of the fluid 58 in the brake system 36 toset the desired level of fluid 58. The ribbed portion 100 of the gasket92 again flexes downward slightly as shown in FIG. 6.

Next, the cap 112 is removed from the sight glass 66, and the sightglass 66 is moved from the raised position to the lowered position. Thepushing of the sight glass 66 to the lowered position introduces airinto the reservoir 56. The introduction of air is important because itallows the proper refractory characteristics for the sight glass 66 toproperly indicate the level of the fluid 58 within the reservoir 56.Without the introduction of the air into the reservoir 56, the sightglass 66 may provide an inaccurate indication of the fluid level. Asshown in FIG. 7, as the middle portion 72 passes through the apertures60, 96, a gap 116 is created between the gasket 92 and the middleportion 72 allowing air to vent into the reservoir 56 under the gasket92. The air pressure below the gasket 92 equalizes with the air pressureabove the gasket 92 and the ribbed portion 100 of the gasket 92 isallowed to return to its original position.

As shown in FIG. 8, the sight glass 66 is moved to the lowered positionwhere the top portion 68 seals against the gasket 92 and seals thereservoir 56. The top flange 74 resists movement of the sight glass 66further into the reservoir 56, and the interference between the topportion 68 and the gasket 92 resists movement of the sight glass 66 outof the reservoir 56. In this position, the top 118 of the sight glass 66is exposed and provides a visual indication of the level of the fluid 58within the reservoir 56. When full, the entire circular top surface 118of the sight glass 66 will be darkened. As the fluid level decreases,the circular darkened area of the top surface 118 will becomeconcentrically smaller.

After the sight glass 66 is moved to the lowered position, the bleederfitting 108 is closed and the adapter 40 is removed from the bleederfitting 108.

Thus, the invention provides, among other things, a brake system fillprocess that can fill the brake system without removing the cover of themaster cylinder assembly. The ability to fill the brake system whilemaintaining the cover connected reduces the likelihood of cosmeticdamage to the motorcycle caused by spillage of the brake fluid anddecreases the process cycle times thereby reducing the cost tomanufacture the motorcycle. Various features and advantages of theinvention are set forth in the following claims.

1-8. (canceled)
 9. A master cylinder assembly for a brake system of a motorcycle, the master cylinder assembly comprising: a housing; a cover coupled to the housing to define a reservoir adapted to contain a fluid at a level, the cover including an aperture; a sight glass received within the aperture and adapted to indicate the level of the fluid within the reservoir, the sight glass having a top portion, a bottom portion, and a middle portion between the top and bottom portions, the top and bottom portions each having a perimeter sized to be received within the aperture and to seal the reservoir, the middle portion having a reduced perimeter relative to the top and bottom portions, wherein the sight glass is movable between a raised position where the bottom portion is received within the aperture and seals the reservoir and a lowered position where the top portion is received within the aperture and seals the reservoir, and wherein the middle portion allows fluid flow through the aperture when the sight glass is moved from the raised position to the lowered position.
 10. The master cylinder assembly of claim 9, further comprising a gasket within the aperture, the gasket being compressed between the top portion and the cover when the sight glass is in the lowered position and being compressed between the bottom portion and the cover when the sight glass is in the raised position.
 11. The master cylinder assembly of claim 9, wherein the top portion includes a top flange that has an increased perimeter from the top portion, the top portion resisting movement of the sight glass into the reservoir beyond the lowered position.
 12. The master cylinder assembly of claim 11, wherein the top flange includes a tapered top edge.
 13. The master cylinder assembly of claim 9, wherein the bottom portion includes a bottom flange that has an increased perimeter from the bottom portion, the bottom portion resisting movement of the sight glass out of the reservoir beyond the raised position.
 14. The master cylinder assembly of claim 9, wherein the sight glass is hourglass-shaped.
 15. A motorcycle comprising: a frame; a front wheel rotatably coupled to the frame; a rear wheel rotatably coupled to the frame; and a braking system selectively operable to slow rotation of at least one of the front and rear wheels, the braking system including a master cylinder assembly having a housing, a cover coupled to the housing to define a reservoir adapted to contain a fluid at a level, the cover including an aperture, and a sight glass received within the aperture and adapted to indicate the level of the fluid within the reservoir, the sight glass having a top portion, a bottom portion, and a middle portion between the top and bottom portions, the top and bottom portions each having a perimeter sized to be received within the aperture and to seal the reservoir, the middle portion having a reduced perimeter relative to the top and bottom portions, wherein the sight glass is movable between a raised position where the bottom portion is received within the aperture and seals the reservoir and a lowered position where the top portion is received within the aperture and seals the reservoir, and wherein the middle portion allows fluid flow through the aperture when the sight glass is moved from the raised position to the lowered position.
 16. The motorcycle of claim 15, further comprising a gasket within the aperture, the gasket being compressed between the top portion and the cover when the sight glass is in the lowered position and being compressed between the bottom portion and the cover when the sight glass is in the raised position.
 17. The motorcycle of claim 15, wherein the top portion includes a top flange that has an increased perimeter from the top portion, the top portion resisting movement of the sight glass into the reservoir beyond the lowered position.
 18. The motorcycle of claim 17, wherein the top flange includes a tapered top edge.
 19. The motorcycle of claim 15, wherein the bottom portion includes a bottom flange that has an increased perimeter from the bottom portion, the bottom portion resisting movement of the sight glass out of the reservoir beyond the raised position.
 20. The motorcycle of claim 15, wherein the sight glass is hourglass-shaped. 